Method of centrifugal molding



May 8, 1934., H. M. NAUGLE ET AL. 1,957,713

METHOD OF CENTRIFUGAL MOLDING Filed Dec. 29, 1931 2 Sheets-Sheet l IN VEN TORS H MNall gle A. J Zbwnsend 7 4% ATTORNEYS y W34 H. M. NAUGLE ET AL 1,957,718

METHOD OF CENTRIFUGAL MOLDING Filed Dec. 29, 1931 2 Sheets-Sheet 2 HMNzuy/e A J Tawrm-eizd 7M A TTORNEYS INVENTORS &

Patented May 8, 1934 UNITED STATES PATENT OFFICE METHOD OF CENTRIFUGAL MOLDING Harry M. Naugle and Arthur J. Townsend, Canton, Ohio, assignors, by mesne assignments, to Rotary Steel Company, Wilmington, Del., a corporation of Delaware Application December 29, 1931, Serial No. 583,658

3 Claims.

It is, therefore, an object of the present invention to prevent thehformation of objectionable cavities or openings in certain portions or regions of a centrifugally molded ring by controlling the rate of cooling and solidifying of the molten metal which forms the ring, so that shrinkage of the metal away from the place of final cooling and solidifying will not cause the formation of cavities or openings and will bring the place or region of final cooling and solidifying at or very close to the inner face of the ring substantially in its median plane.

We have discovered that the rate of cooling and solidifying of the molten metal may be controlled by applying a coating or blanket of heat insulating material to the inner face of the ring immediately after the molten metal has been poured, as set forth in our prior application filed September 18, 1931, Serial No. 563,583, matured as Patent No. 1,908,169, dated May 9, 1933; and the present invention is a specific improvement upon one of the methods set forth in said prior application.

To that end we have discovered that the rate of cooling and solidifying of centrifugally molded rings may be most satisfactorily controlled by applying a coating or blanket of comminuted refractory material to the inner face of the ring, which does not fuse at the temperatures occurring at the inner face of the ring.

Accordingly, one of the principal objects of the 5 present improvement is to control the rate of cooling and solidifying of a centrifugally molded ring by applying a coating or blanket of comminuted refractory material to the inner face of the ring. Furthermore, we have discovered that if the heat insulating coating or blanket applied upon the inner face of a centrifugally molded ring is formed of comminuted refractory material, gases and the like which may be contained in the molten metal are permitted to escape from the molten metal while the same is solidifying in the mold.

Moreover, we have discovered that finely divided or comminuted refractory or heat insulating materials which do not fuse and solidify at the temperatures occurring at the inner face of a centrifugally molded ring produce a pressure, by the action of centrifugal force, on the inner face of the ring which assists in producing a molded ring in which the metal is uniform and homogeneous throughout, free from objectionable cavities and/ or openings.

It is therefore, a further object of the present invention to utilize, in centrifugally molding rings,

a heat insulating coating or blanket which will permit the escape of gases and the like from the molten metal which is solidifying, and which will exert a pressure by the action of centrifugal force upon the molten metal which is solidifying in the mold.

We have also discovered that a very satisfactory heat insulating coating or blanket for centrifugally molding rings may be formed by using a finely divided heat insulating refractory material which does not fiux in the presence of slagging agents, which may exist in or form from the metal and/ or the refractory material, to fuse at temperatures occurring at the inner face of the ring.

It is therefore a further object of the present invention to control the cooling of molten metal contained within a rotating annular mold by applying to the inner face of the molten metal a heat insulating coating or blanket of comminuted refractory material which does not fuse at the temperatures occurring at the inner face of the ring, and which does not flux in the presence of slagging agents which may exist in or form from the metal or the refractory material, to fuse at temperatures occurring at the inner face of the ring.

We have also discovered that the cooling of a centrifugally molded ring may be quite accurately and effectively controlled by utilizing a heat insulating coating or blanket formed of comminuted refractory material, because such material may be readily, quickly and easily applied to the inner face of the ring in a rotating mold in accurately measured quantities to spread or distribute the same substantially evenly over the entire inner face of the ring.

We have discovered that comminuted refractory materials possessing the properties or characteristics necessary for accomplishing the purposes of the present invention may be comminuted mineral, rocky, argillaceous or earthy materials, and more specifically may be fire clay, infusorial earth, bauxite, burned calcite, corundum,

chrome ore, dolomite, diaspore, g'anister, gibbsite, kaolin, lime, limestone, magnesite, mullite, quartz, sillimanite, spinel, or other finely divided heat insulating refractory materials which do not fiux in the presence of slagging agents which may exist in or form from the molten metal or the refractory material to fuse at temperatures occurring at the inner face of the ring.

In referring to "comminuted refractory material" herein, it is intended that the material may be one particular kind of comminuted refractory material, or may be a mixture or combination of any two or more kinds of comminuted refractory material, a number of kinds of which have been specifically set forth hereinabove.

It is quite difiicultto apply finely divided or comminuted material to the inner face of molten metal contained within a rotating annular mold without distributing the same throughout the atmosphere surrounding the rotating mold, but we have discovered that preferably, measured quantities of comminuted refractory material may be placed in a container and dropped or impinged against the inner face of the molten metal, where the container, which may be paper or fabric, is destroyed, while the finely divided or comminuted material is substantially evenly distributed or spread over the inner face of the ring to form a heat insulating coating or blanket, without any substantial portion of the finely divided material being released to the surrounding atmosphere.

The principal purposes of the present improvements, thus set forth in general terms, and an cillary advantages in the operation of rotary molds for making metal rings, have been success- 7 fully accomplished by means of apparatus such asis illustrated in the accompanying drawings forming part hereof, in which:

Figure 1 is an axial elevation section of a portion of a centrifugal molding machine showing a supporting table with an annular ring mold thereon, and showing means for applying comminuted material to the inner face of a ring being molded therein; and

Fig. 2 is an enlarged cross section of a portion of the improved annular ring mold.

Similar numerals refer to similar parts throughout the drawings.

The centrifugal molding machine preferably includes a round table 5 mounted on a vertical axis, for rotating upon a supporting base 6 by driving gearing 7 provided with roller bearings 8 and 8a to insure an even, steady and uniform rotation of the table at a high rate of speed, which may be some 200 R. P. M.

The mold may include substantially similar opposing sections, each upper and lower section of the mold being divided into an outer and inner part, respectively 9a, 9b, 9a and 9b, the division between the inner and outer parts being by substantially vertical joints 10 and 10a having an offset 10b therein, so that the inner parts 917 and 9b may be readily detached for replacement; but the inner parts 91) and 9b are normally secured to the outer parts 9a and 911' as by means of rings 11 bearing upon shoulders 12 on the outer parts, and assembled by bolts 13.

Flanges 14 and key bolts 15 are provided for detachably securing the upper and lower sections together, there being a substantially horizontal joint 16 with anoifset 16a therebetween, substantially in the median plane of the mold; and a flange 17 may be provided on the upper section by means of which the upper section or both sections may be raised and carried by a suitable crane tackle, not shown.

The annular mold cavity 18 is suitably shaped to give the desired section to a massive ring, preferably with the upper and lower sides of the mold slightly tapered outward toward each other, with rounded corners at the outer side of the mold; and the lower side of the mold may be extended inward by means of a replaceable annular wear plate 19, for receiving and flowing molten metal into the mold cavity.

The mold as a whole, or its separable lower section, may be centrally located and maintained on the rotary table by means of a centering ring or a plurality of blocks 20, which may be secured as by welding 21 upon the top of the table 5.

A molten metal pouring box 22 is removably supported and suspended as by a frame 23 movable upon a support, not shown; which box is provided with a discharge spout 44 located adjacent the inner side of the mold and directed to discharge molten metal substantially tangentially upon the annular plate 19, whence the metal flows by the action of centrifugal force outward into the mold cavity when the machine is rotated, as shown in Fig. 1.

An annular ring of heat insulating refractory material 24 is preferably inserted in an annular channel 25 provided for that purpose in the upper wall of the mold, to face a portion of the mold cavity adjacent the inner portion thereof; which ring may be made of a series of arcuate fire brick dovetailed into the channel and secured therein as by fire clay cement 26.

A similar annular ring 24 of heat insulating refractory material is inserted in an annular channel 25' provided for that purpose in the lower wall of the mold, to face a portion of the mold cavity at and adjacent the inner portion thereof; which ring may be made of a series of arcuate fire brick dovetailed into the channel and secured therein as by fire clay cement 26, all as well shown in Fig. 2.

A similar annular zone of heat insulating refractory material 27 is inserted in an annular channel 28 provided for that purpose in the upper side of the wear plate 19, and extending from the outer corner thereof to a point adjacent the inner corner thereof, to receive and insulate the molten metal as it is poured upon the wear plate; and this zone may be made of a series of arcuate fire brick dovetailed into the channel 28 and secured therein, as by fire clay cement 29, also shown in Fig. 2.

A cartridge chute 30, provided with a flared receiving end 31 and an open discharge end 32 is also suspended or mounted on the frame 23 for holding a cartridge charge of comminuted refractory material; and such material or materials generally indicated at 32 may be confined in measured amounts within a paper or fabric container or receptacle 33 and held within the cartridge chute 30 by a bell crank stop 34 pivoted at 35 to the chute 30, and maintained in position by a trigger 36 which may be operated by a pull chain 37 leading to the operators station.

In operating the rotary mold, molten metal at a temperature above 2600 F. is poured upon the table from the pouring box spout 44, the molten 45 A is formed, as conventionally shown in Figs.'1'1

and 2; and immediately thereafter the cartridge B containing comminuted refractory material, is released by the trigger chain 3'7 and moves downward therein to the discharge end 32 of the chute 30, where the paper or fabric container or receptacle 33 is destroyed, due to its proximity to or contact with the molten metal forming the ring A. The comminuted material immediately spreads over the inner surface of the molten metal to form a heat insulating coating or blanket shown by dotted lines at D on the inner face C of the formed ring.

Alternately, a measured amount of comminuted, refractory material may be confined within a paper container or receptacle 33, and held within the chute 30 until it is desired to spread the same over the inner surface of the molten metal forming the ring A; at which time the paper container or receptacle may be split, opened, or severed, in any suitable manner, preferably at its lower end, to permit the comminuted material to be discharged from the discharge end 32 of the chute and be impinged against and spread over the inner surface of the molten metal to form a heat insulating coating or blanket on the inner face of the formed ring.

The use of comminuted, refractory material to form a-heat insulating coating or blanket on the inner face of the formed ring retards the cooling of the metal at and adjacent the inner face of the ring until the cooling of the metal has progressed inward from the outer and upper and lower portions of the ring substantially entirely to the inner face thereof, so that the final cooling and solidifying will occur at or about z, as shown in Fig. 2.

After the coating or blanket of comminuted refractory material has been applied to the inner face of the ring A, rapid rotation of the annular mold is continued, so as to maintain centrifugal pressure until the 'metal has cooled to a selfsustaining, plastic condition whereupon the centrifugal pressure is reduced until the metal has further cooled to permit the ring to shrink with- ,out a granular disintegration of the metal.

The presence of the insulating zone 27 in the annular wear plate 19 in the improved mold, and

the adjoining insulating ring 24' in the lower section of the mold, prevent a premature cooling of the molten metal as it is poured and flows upon the same, and prevent the formation of a flange or fin upon the inner lower comer of the ring A.

And the presence of the insulating ring 24 in the upper section of the mold likewise prevents the formation of a fin at the inner upper corner of the ring A, so that the inner face C of the ring is formed without any formations or fins upon its inner comers, as shown in Fig. 2, thus having the waste and expense of removing the same before the ring can be cut into sections and thereafter rolled into the desired semi-finished or finished product.

It is not intended to limit the scope of the present invention to the refractory materials specifically enumerated herein, because the purposes of the present invention may be accomplished by utilizing some other comminuted refractory material possessing the required characteristics.

We claim:-

l. The method of making a ring from molten metal in a rotating annular mold, which includes confining comminuted, refractory material within a receptacle, flowing molten metal into the mold until the ring is formed, and discharging the comminuted material from the receptacle to impinge the same against the inner face of the ring and spread a blanket of comminuted material over the inner face of the ring.

2. The method of making a ring from molten metal in a rotating annular mold, which includes confining comminuted, refractory material within a receptacle, flowing molten metal into the mold until the ring is formed, and discharging the receptacle against the inner face of the ring to destroy the receptacle and spread a blanket of comminuted material over the inner face of the ring.

3. The method of making a ring from molten metal in a rotating annular mold, which includes confining a measured amount of comminuted, refractory material within a receptacle, flowing molten metal into the mold until the ring is formed, and discharging the receptacle against the inner face of the ring to destroy the receptacle and spread a blanket of comminuted material over the inner face of the ring.

HARRY M. NAUGLE. ARTHUR J. TOWNSEND. 

